1. Field of the Disclosure
The present disclosure relates to a light emitting diode and a method of fabricating the same, and more particularly, to a light emitting diode and a method of fabricating the same with an improved structure capable of increasing the light emitting efficiency and the light output efficiency.
2. Description of the Related Art
A light emitting diode (LED) is a semiconductor device, which emits light by electrons moving from a point of high energy level to a point of low energy level when an electric power is applied to it. A LED consumes 1/12 of the power of the conventional light source, and has 100-time longer life time, and 1000-time faster response speed than the conventional light source. Moreover, the LED emits light of high brightness with low power consumption, and is regarded as the optimal light source for very large electric display signs. The light color of the LED varies depending on which compound material is used, such as GaP or GaAs. Red and green LEDs were developed decades ago and have been used widely in various industrial fields and in home electronic appliances.
The LED is categorized into a top-emitting light emitting diode (TLED) and a flip-chip light emitting diode (FCLED) according to the direction of the light. The TLED emits light through a p-type compound semiconductor layer and a p-type electrode which forms an ohmic contact. The p-type electrode is a stack of Ni and Au loaded sequentially on the p-type compound semiconductor layer. However, the p-type electrode formed of Ni and Au is semi-transparent, and the TLED in which the p-type electrode is applied has a low light utility efficiency and a low luminescence character. In the FCLED, light generated in an active layer is reflected on a reflection electrode formed on the p-type compound semiconductor layer, and the reflected light is emitted through the substrate. The reflection electrode is formed of a material having a high light-reflective characteristic, such as Ag, Al, and Rh. A FCLED in which the reflection electrode is applied has a high light utility efficiency and a high luminescence characteristic.
A LED with a micro-reflector structure has been developed to enhance the light output efficiency of a conventional LED. When fabricating a LED with a micro-reflector structure using nitride semiconductors, an uneven structure can be obtained by etching a p-GaN layer or etching the lower part of an active layer. However, in an uneven structure obtained by etching a p-GaN layer, current injection may be problematic because of the thickness reduction of the p-GaN layer. Also, in an uneven structure obtained by etching the lower part of the active layer, light emitting efficiency may be reduced due to the reduction of the area of the active layer. In addition, an electric insulation layer is required between an n-GaN layer and a p-GaN layer, thereby complicating the electrode formation process. Therefore, an improved structure for improving the light emitting efficiency and the light output efficiency of the LED is needed.